Certain machine tools such as lathes possess a vertically-mounted spindle on whose underside an adjustable chuck is provided. Such a lathe is known from DE 10 2004 029 916 A1. This known machine tool includes a switchable platform that may be set at various positions, whereby the pieces to be worked on are tensioned at the edges of the switchable platform using the available securing system. This tensioning occurs at the outer edge of the turntable-shaped switchable platform so that during the exchange of pieces being worked should these pieces have varying diameters, a reconfiguration of the adjustable chuck is required. If alternative tensioning using electromagnets occurs, a programming alteration is required in order to recalculate the travel path of the spindle at the transition location. The use of a large number of adjustable chucks and this reprogramming are time-consuming and expensive.
DE 198 47 284 A1 describes a vertical lathe with a transport device that is designed as a continuous transport chain (conveyor). This transport conveyor includes recesses for pieces to be worked on. The pieces are positioned on the recesses but not centered. The pieces to be processed are centered by means of a centering device and secured in this position so that they may be received into the receptor position by the spindle. The centering device possesses a specific design height so that pieces to be worked are secured by it and will no longer be accepted by the adjustable chuck of the spindle if the height of these pieces is approximately the same as the height of the centering device.